A Case of Myxoid Adrenocortical Carcinoma With 1p Deletion Identified by Whole Exome Sequencing

A 57-year-old male underwent an incidental left adrenal tumor resection because of malignancy concerns. The tumor demonstrated a heterogeneous yellowish-white color. Histological features were characterized by nuclear atypia, diffuse growth, sinusoidal invasion, and mucin deposition in most stromal regions, leading to the diagnosis of a myxoid adrenocortical carcinoma (ACC). Whole exome sequencing analysis revealed 1p deletion and other several mutations without TP53 nor CTNNB1 mutations. Following surgery and adjuvant mitotane therapy, the patient showed no recurrence at a 5-year follow-up. Myxoid ACC is an exceedingly rare tumor characterized by mucus deposits in tumor stroma with high malignant potential. Despite the identification of crucial driver gene mutations such as TP53 and CTNNB1 in ACC, the genetic background of the myxoid ACC remains unclear. This case was the first case report of myxoid ACC with a 1p deletion, which was reported to be detected in 67% of ACC and 9% of adenoma but not in hyperplasia, supporting the correlation of this aberration with tumorigenesis. In conclusion, 1p deletion may be relevant to tumorigenesis in myxoid ACC.